Calorie Calculator

How Calorie Calculator works

Estimate basal metabolic rate and daily calories for maintenance, weight loss or weight gain. Everything happens inside this page: the tool reads your input, runs the calculation or conversion locally, and hands the result back to you. Nothing is transmitted, because there is no backend to transmit it to.

That design choice is deliberate. Most free tool sites upload your files to a server, process them there, and quietly keep a copy. Toolcin cannot do that — the site is a set of static files. If your connection dropped the moment the page finished loading, every tool would still work.

The Mifflin–St Jeor equation

Basal metabolic rate is estimated as 10 × weight(kg) + 6.25 × height(cm) − 5 × age + s, where s is +5 for men and −161 for women. It is the equation most dietetics bodies recommend over the older Harris–Benedict formula, because it tracks measured values more closely in modern populations.

Maintenance calories are BMR multiplied by an activity factor. The five options run from 1.2 for a desk job to 1.9 for twice-daily training — a span that changes the daily figure by more than 50%.

The ±550 kcal targets

The tool shows maintenance, a −550 kcal target and a +550 kcal target, which correspond to roughly 0.5 kg of fat per week in either direction. The usual figure is 7,700 kcal per kilogram of fat, so 550 × 7 ≈ 3,850 kcal a week — half a kilogram.

That arithmetic assumes the deficit is sustained and that the body does not adapt. Real weight change slows over time as mass and activity change, so the same deficit produces less movement in month six than in month one.

What this cannot know

Body composition, medical conditions, medication, sleep and thyroid function all shift actual expenditure well away from the equation's estimate. The figure is a starting point for a two-week experiment: eat at it, track weight, then adjust based on what actually happened.

Nothing here is medical or dietary advice, and a very low target is a reason to speak to a clinician, not to eat less.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions

How this number is produced

The calculation is Mifflin–St Jeor BMR multiplied by an activity factor from 1.2 to 1.9, following Mifflin & St Jeor, 1990. The formula is repeated here so the result can be checked by hand rather than taken on trust.

This is a calculator, not advice. No clinician, accountant or adviser has reviewed it, and it cannot see your circumstances. For anything involving health, a loan, a tax filing or a religious obligation, confirm the figure with a qualified professional or the authority that publishes the rule.